1. Field of the Invention
The invention is directed to tobacco and reconstituted tobacco smoking compositions and products and methods of making them. More specifically, it relates to such compositions and products and methods which result in substantially reduced quantities of carbon monoxide in the smoke produced when smoking such products.
Reconstituted tobacco smokable compositions and products are well-known. One way of producing reconstituted tobacco is to extract the soluble ingredients of natural tobacco, which preferably has been macerated or comminuted in preparation for extraction. The extraction may be performed using water, and generally from 30 to 55% of the weight of the starting material is withdrawn. An aqeous slurry is then formed containing the fibers and, by ordinary papermaking techniques, the slurry (with or without additives) is transformed into a self-sustaining web. The tobacco extract, which may be concentrated to a liquor, may be then introduced into the web. The application of the extracted tobacco may be achieved in any appropriate manner, as by spraying, saturating or otherwise.
Natural tobacco smoking compositions and products utilizing leaves, lamina, stem or stock, are also well-known. Such natural tobacco compositions (with or without additives) may be shredded or otherwise subdivided and the shreds or particles formed into rods which are wrapped to form cigarettes. Such compositions may, of course, be utilized in other forms as pipe tobacco or, in whole leaf form, as wrappers for cigars and the like.
In all of these forms, when smoked, there is a resulting production of carbon monoxide which is generally recognized as undesirable. There is, therefore, a need to produce such compositions and smoking tobacco products that result in reduced production of carbon monoxide.
2. Description of the Prior Art
The addition of salts to effect changes in combustion is known. For example, Briskin and Ward U.S. Pat. No. 3,612,063 dated Oct. 12, 1971 teaches the addition of low levels (less than 2% by weight) of potassium salts of certain organic acids to oxidize cellulose for the purpose of controlling burn. U.S. Pat. No. 3,556,109, also to Briskin and Ward issued Jan. 19, 1971 teaches that high levels (up to 30%) of alkaline earth salts of carboxylic acids modify the ash forming characteristics of cellulose materials. There are other patents concerned with modifications of cellulosic webs, in contradistinction to tobacco for reconstituted tobacco materials; for example, U.S. Pat. No. 4,197,861 to Keith issued April 15, 1980 describes the addition of alkali and alkaline earth metal salts of carbonic acids in minor amounts (0.5 to 5%) to cellulose based synthetic smoking materials to impart a commercially acceptable burning rate to the material. Such patents fail to suggest that alkali-metal salts of carboxylic acids at any addition levels result in a reduction in the generation of carbon monoxide. U.S. Pat. No. 3,924,642 to Eicher, Muller and Krebs issued Dec. 9, 1975 discloses the treatment of cellulosic webs with mixed salts (salts of alkaline earth metals and iron or aluminum) of chelate-forming carboxylic acids. The patent teaches the addition of from 0.01% to 7% of alkali-metal or alkaline earth metal nitrates or alkali-metal permanganates, as oxidizing agents, neither of which compounds (either in the amounts claimed or in higher amounts) produces nearly the desired effect of reducing the level of carbon monoxide generated without introducing extremely fast burn rates and an increase in undesirable compounds in the smoke. U.S. Pat. No. 4,296,762 to Eicher and Muller dated Oct. 27, 1981 discloses a method for the addition of finely divided inorganic fillers (such as oxides, hydroxides or hydrated oxides of aluminum, iron, manganese, zinc, titanium and silicon) to synthetic smoking materials based on cellulose. As an aid to dispersing these inorganic fillers, patentees suggest the use of alkali-metal, ammonium, alkaline earth metal, iron, aluminum, manganese or zinc salts of carboxylic acids, preferably as chelate salts. In general these patents relate to the treatment of cellulose based or other synthetic smoking materials.
The treatment of tobacco or reconstituted tobacco is also known. For example, U.S. Pat. No. 3,760,815 to Deszyck issued Sept. 25, 1973 teaches that the addition of ammonium salts of organic acids to tobacco releases tobacco pectins from the tobacco; as mentioned above, addition of these ammonium salts of carboxylic acids has no salubrious effect upon the generation of carbon monoxide. U.S. Pat. No. 4,006,749 to Horowitz, Dichter and Abrams issued Feb. 8, 1977 describes a process for grafting onto tobacco vinyl polymers containing, in one variation, functional groups that include the carboxyl moiety; the purpose of this modification is to scavenge alkaline compounds from the smoke. U.S. Pat. No. 4,033,359 to Borthwick and Morman issued July 5, 1977 discloses the addition of small amounts of potassium citrate (3.9% to 4.3%) to tobacco based smoking mixtures for the purpose of obtaining acceptable rates of combustion; at these levels of addition burn acceleration, not retardation, occurs and there is no favorable influence over the generation of carbon monoxide. Finally, U.S. Pat. No. 4,119,104 to Roth issued Oct. 10, 1978 teaches the addition of nitrates and citrates as burn accelerators to tobacco substitutes; in patentee's type of smoking mixture, the addition of high levels of alkali-metal salts of carboxylic acids does indeed have the effect of increasing the rate of burn, but there is no favorable effect upon the combustion which would reduce the generation of carbon monoxide.